/*
 * @(#)Images.java
 *
 * Copyright (c) 1996-2010 by the original authors of JHotDraw and all its
 * contributors. All rights reserved.
 *
 * You may not use, copy or modify this file, except in compliance with the 
 * license agreement you entered into with the copyright holders. For details
 * see accompanying license terms.
 */
package org.jhotdraw.util;

import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.Image;
import java.awt.RenderingHints;
import java.awt.Toolkit;
import java.awt.Transparency;
import java.awt.image.BufferedImage;
import java.awt.image.ColorModel;
import java.awt.image.PixelGrabber;
import java.awt.image.Raster;
import java.awt.image.RenderedImage;
import java.awt.image.WritableRaster;
import java.net.URL;

import javax.swing.ImageIcon;

/**
 * Image processing methods.
 * 
 * @author Werner Randelshofer
 * @version $Id: Images.java 717 2010-11-21 12:30:57Z rawcoder $
 */
public class Images {

	/** Prevent instance creation. */
	private Images() {
	}

	public static Image createImage(Class baseClass, String resourceName) {
		URL resource = baseClass.getResource(resourceName);
		if (resource == null) {
			throw new InternalError("Ressource \"" + resourceName + "\" not found for class " + baseClass);
		}
		Image image = Toolkit.getDefaultToolkit().createImage(resource);
		return image;
	}

	public static Image createImage(URL resource) {
		if (resource == null) {
			throw new IllegalArgumentException("resource must not be null");
		}
		Image image = Toolkit.getDefaultToolkit().createImage(resource);
		return image;
	}

	/**
	 * Converts an Image to BufferedImage. If the Image is already a
	 * BufferedImage, the same image is returned.
	 * 
	 * @param rImg
	 *            An Image.
	 * @return A BufferedImage.
	 */
	public static BufferedImage toBufferedImage(RenderedImage rImg) {
		BufferedImage image;
		if (rImg instanceof BufferedImage) {
			image = (BufferedImage) rImg;
		} else {
			Raster r = rImg.getData();
			WritableRaster wr = WritableRaster.createWritableRaster(r.getSampleModel(), null);
			rImg.copyData(wr);
			image = new BufferedImage(rImg.getColorModel(), wr, rImg.getColorModel().isAlphaPremultiplied(), null);
		}
		return image;
	}

	public static BufferedImage toBufferedImage(Image image) {
		if (image instanceof BufferedImage) {
			return (BufferedImage) image;
		}

		// This code ensures that all the pixels in the image are loaded
		image = new ImageIcon(image).getImage();

		// Create a buffered image with a format that's compatible with the
		// screen
		BufferedImage bimage = null;

		if (System.getProperty("java.version").startsWith("1.4.1_")) {
			// Workaround for Java 1.4.1 on Mac OS X.
			// For this JVM, we always create an ARGB image to prevent a class
			// cast exception in
			// sun.awt.image.BufImgSurfaceData.createData(BufImgSurfaceData.java:434)
			// when we attempt to draw the buffered image.
			bimage = new BufferedImage(image.getWidth(null), image.getHeight(null), BufferedImage.TYPE_INT_ARGB);
		} else {
			// Determine if the image has transparent pixels; for this method's
			// implementation, see e661 Determining If an Image Has Transparent
			// Pixels
			boolean hasAlpha;
			try {
				hasAlpha = hasAlpha(image);
			} catch (IllegalAccessError e) {
				// If we can't determine this, we assume that we have an alpha,
				// in order not to loose data.
				hasAlpha = true;
			}

			GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
			try {
				// Determine the type of transparency of the new buffered image
				int transparency = Transparency.OPAQUE;
				if (hasAlpha) {
					transparency = Transparency.TRANSLUCENT;
				}

				// Create the buffered image
				GraphicsDevice gs = ge.getDefaultScreenDevice();
				GraphicsConfiguration gc = gs.getDefaultConfiguration();
				bimage = gc.createCompatibleImage(image.getWidth(null), image.getHeight(null), transparency);
			} catch (Exception e) {
				// } catch (HeadlessException e) {
				// The system does not have a screen
			}

			if (bimage == null) {
				// Create a buffered image using the default color model
				int type = BufferedImage.TYPE_INT_RGB;
				if (hasAlpha) {
					type = BufferedImage.TYPE_INT_ARGB;
				}
				bimage = new BufferedImage(image.getWidth(null), image.getHeight(null), type);
			}
		}

		// Copy image to buffered image
		Graphics g = bimage.createGraphics();

		// Paint the image onto the buffered image
		g.drawImage(image, 0, 0, null);
		g.dispose();

		return bimage;
	}

	/**
	 * This method returns true if the specified image has transparent pixels
	 * 
	 * Code taken from the Java Developers Almanac 1.4
	 * http://javaalmanac.com/egs/java.awt.image/HasAlpha.html
	 */
	public static boolean hasAlpha(Image image) {
		// If buffered image, the color model is readily available
		if (image instanceof BufferedImage) {
			BufferedImage bimage = (BufferedImage) image;
			return bimage.getColorModel().hasAlpha();
		}

		// Use a pixel grabber to retrieve the image's color model;
		// grabbing a single pixel is usually sufficient
		PixelGrabber pg = new PixelGrabber(image, 0, 0, 1, 1, false);
		try {
			pg.grabPixels();
		} catch (InterruptedException e) {
		}

		// Get the image's color model
		ColorModel cm = pg.getColorModel();
		return cm.hasAlpha();
	}

	/**
	 * Splits an image into count subimages.
	 */
	public static BufferedImage[] split(Image image, int count, boolean isHorizontal) {
		BufferedImage src = Images.toBufferedImage(image);
		if (count == 1) {
			return new BufferedImage[] { src };
		}

		BufferedImage[] parts = new BufferedImage[count];
		for (int i = 0; i < count; i++) {
			if (isHorizontal) {
				parts[i] = src.getSubimage(src.getWidth() / count * i, 0, src.getWidth() / count, src.getHeight());
			} else {
				parts[i] = src.getSubimage(0, src.getHeight() / count * i, src.getWidth(), src.getHeight() / count);
			}
		}
		return parts;
	}

	/**
	 * Creates a scaled instanceof the image.
	 * <p>
	 * If either width or height is a negative number then a value is s
	 * ubstituted to maintain the aspect ratio of the original image dimensions.
	 * If both width and height are negative, then the original image dimensions
	 * are used.
	 * <p>
	 * On Mac OS X 10.6, this method has a much better performance than
	 * BufferedImage.getScaledInstance.
	 * 
	 * 
	 * @param image
	 *            the image.
	 * @param width
	 *            the width to which to scale the image.
	 * @param height
	 *            the height to which to scale the image.
	 */
	public static BufferedImage getScaledInstance(Image image, int width, int height) {
		int w, h;
		if (width < 0 && height < 0) {
			w = image.getWidth(null);
			h = image.getHeight(null);
		} else if (width < 0) {
			w = image.getWidth(null) * height / image.getHeight(null);
			h = height;
		} else if (height < 0) {
			w = width;
			h = image.getHeight(null) * width / image.getWidth(null);
		} else {
			w = width;
			h = height;
		}

		BufferedImage scaled = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
		Graphics2D g = scaled.createGraphics();
		g.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BICUBIC);
		g.drawImage(image, 0, 0, w, h, null);
		g.dispose();

		return scaled;
	}
}
